Oddly enough, this counterfeiter's saving grace was that he only counterfeited one dollar bills, and did so at such a slow rate that he was able to stay under the radar. Despite the fact that his counterfeit bills were so low-quality that some of them even spelled "Washington" wrong ("Wahsington"), this guy was able to stay out of trouble by only producing 40-50 one dollar bills every month, and avoiding making return visits to the same stores.
The Secret Service was looking for this counterfeiter for 10 years. Ultimately, he was brought down by a bunch of kids who discovered some discarded fake bills near his apartment and were caught using the fake money as toys. As it turns out, the elusive counterfeiter was a 73-year-old retiree who was using the fake bills to make ends meet. He served 4 months in prison for his crimes.
In case you were wondering, in addition to providing security for the President, Vice President and their families, the Secret Services primary responsibilities are investigating fraud and counterfeiting.
Read more about the unusual case of the $1 counterfeiter, "Old Mr. Eighty-Eight".